City of Heavenly Fire
by iLoveMeSomeCaptainAmerica
Summary: He's coming. They don't know when. They don't know how. But they know. As their world slowly begins to fall apart, Nephilim and Downworlders alike are forced to band together once again in hopes to restore balance. Promises will be broken, lives will be lost, and love will be put to the ultimate test. "Are you ready?"
1. Prologue

**_Disclaimer: I do not own any of Cassandra Clare's characters._**

**_This version of how I'm interpreting the final installment of the Mortal Instruments series is based off of spoilers, spoiler art, and my own imagination. _**

**_This will be a darker fic and there WILL be material not suitable for some readers. THIS IS YOUR WARNING._**

**_Unlike how the real books are, my story will mainly revolve around Jace, Clary, and Sebastian. But don't think there won't be any Sizzy, Malec, Jaia, Aline and Helen, or Jocelyn and Luke. _**

**_My main purpose for writing this is to ultimately find closure. It's ridiculous that we won't be getting to read the real _****City of Heavenly Fire ****_until 2014. This is me filling the void._**

* * *

_Prologue:_

She'd never known how cruel fate could be.

Numb, in pain, and helpless, her life flashed before her eyes; quick flares of light followed by memories she didn't even know she had and others that could never be forgotten.

Wrapped in a tight bundle, cradled in her mother's arms, looking up at the most brilliant smile and green eyes.

Dressing up as princess Ariel for Halloween.

Making cookies all by herself for the first time––without anyone knowing––and ultimately sending all of Brooklyn's fire department to the Garroway residence.

Watching movies with Luke from morning till midnight, snacking all day on buttery popcorn and peanut butter M&M's.

Her first day of school, walking through the double doors with Simon by her side, determined, and half the size of all the other little munchkins.

Being the only one in Mrs. Peterson's class to get a hundred percent on the spelling test.

Getting kicked out of Mr. Benson's class for rolling her eyes.

Seeing Jace for the first time, the only light she could unveil in the dark, a mysterious shadow masking the angel he really was.

Their first kiss in the greenhouse, sticky, lips coated with apple juice.

The first time he'd told her "I love you".

Her throat was dry and her limbs, bloodied and bound together, were incapable of moving even the slightest inch. The sky was angry, stained crimson, the clouds like bundles of fire, scorching its former beauty. Death was in the air, she could smell it, but, other than the monster standing before her, she was alone.

Sebastian was smiling at it all: The eerie silence, the blood and its repulsing, salty aroma, his victory. His sister.

"It's beautiful," he said, his demon eyes soulless, unfazed. If Clary could talk, she'd be screaming at the top of her lungs, repeating the nasty and hateful thoughts swarming her mind. How was it that he couldn't feel anything? How was it that he looked so human, so beautiful, yet was a _demon_?

_How was it that he'd won?_

Sebastian leaned over her and shook his head, as if he were speaking down to a naughty toddler. "Bad day?" A terse laugh escaped him as his hands tangled in her hair, yanking her upper body off of the ground a few inches. Clary, even if she didn't have the rune of silence, would have refused to whimper or scream in pain. His fingers curled and twisted, pulling abusively on the thick tendrils, but she set her jaw, unable to keep the tears from welling up in her eyes. Sebastian's face was contorted with sudden rage. "You betrayed me," he seethed.

"I gave you everything, I treated you with more kindness than you deserved, I cared for you... and _you_ stabbed me right in the back." His eyes bore into hers, but she matched his glare, not willing to back down. "And look where that got you, Clarissa. Was this all that you were hoping for?"

Sebastian's fingers contracted before he released his hold altogether and threw her back to the ground. Clary was viscously deprived of air as a merciless kick was aimed at her gut again, and again. And again. "Now, there's no escaping me little sister," he spat, wiping the sweat from his brow with the back of his hand. "There's no one here to save you––not your angel boy, not your pathetic mother or that dog, not the Daylighter––there's no one. You belong to me now."

Breathing heavily, gasping on smoke and blood, Clary, despite the uselessness of it, began to thrash back and forth, her binds growing tighter and tighter, her will to keep conscious growing weaker and weaker._ I'll never belong to you!_ She wanted to shout. _Never._

Sebastian was amused nonetheless. She was so weak, so helpless, so unyielding, but she was all he wanted. She was _his_. "There's still so much fire in you, isn't there?" He scoffed in near disbelief. "I could cut off all of your limbs and you'd still think you could stand a chance.

"Look around you Clarissa!" He cupped his hand around his ear, as if to enhance his hearing, a triumphant smile gracing his features. "There's _nothing_. Everyone's dead. Everyone you care about is under my control. There's _nowhere_ for you to run. You're all mine."

_He's right_, Clary thought bitterly, distantly, the spark inside of her dimming. She was all alone, and her brother––her own _brother_––had free rein to do anything he wanted to her, no matter how brutal. He had all the power in the world.

"Now," Sebastian breathed, flinging her in his arms and over his shoulder, "don't get too excited, but we're going to go burn down the world."


	2. Pockets Full of Posies

**Part 1**

_Pockets Full of Posies:_

**_Jace_**

It was the weirdest sensation to have _fire _run through my veins. I could feel it coursing in my blood, like pieces of drift wood floating down an inanimate river, distinct and bothersome to the human eye, but not at all harmful. I was feverish all the time, and yet, I was never exceedingly hot or in desperate need to cool off. I just felt..._different_.

It almost felt as if the fire needed me as fuel; I always felt drained, like I was _constantly _having to put my energy into something I didn't want to––which actually explained my predicament perfectly. I wanted to be able to sprint a marathon whenever I felt like it, and jump from building to building effortlessly, and, you know, be able to go up a flight of stairs without getting winded.

And, now that I possess the ability to burn others, Mayrse, for some reason beyond me, has deluded herself into thinking that I need to be protected. I mean, come on, I love the woman, but if anything, I'm a threat. It's others that need protecting. _I _shouldn't have to be restricted to my bed just because I can make _her daughter_ into a shish kabob. It's not like having fire within me is a disadvantage––_I can literally roast anyone who poses a threat_. So, her whole "you need to rest until you're better" demand is completely unnecessary.

_Until I'm better..._Huh.

Unless the Silent Brothers can figure anything out, I won't ever be able to 'get better'.

And I'm not saying I like having this new supernatural ability, because I don't. _I hate it_. It's a burden that is on my mind every second of every damn minute. I would say 'of every damn _day_', but I'm not entitled to yet. I've just barely returned home, however, I'm sure that with my current mindset, a couple hours and a couple days won't be any different.

This _curse _has already proven to be a total drag; testing my patience––which, if you haven't already figured this out, sucks––and threatening to drive me right up a wall. Sure, give me the one power that prohibits me from doing the one thing that an average person does about a billion times a day: touch.

The instant I had regained consciousness in the Institute, I had had only one thing on my mind: Clary. Yes, it had been wonderful to see Alec and Isabelle, but I had wanted to see _Clary_. It was terrifying that I felt so strongly for someone, that I would be willing to do anything for her, that I _needed _her, but at the same time, it was assuring. I hadn't ever thought that I'd be capable of such human emotions, but then Clary stepped into the picture and everything––my whole world––had changed. I'm not even sure if my feelings for her were_ human_; I'm not sure if a husband could ever love his wife so much that he'd commit suicide if it meant she'd live, or if he'd ever trust her enough to read him like a novel, or if he'd ever want her as badly as I wanted Clary.

She'd stabbed me––_so hot_––yet I had been so afraid that_ she_ was dead, but then Alec had managed to bring me back down to Earth with the news that she was in fact fine.

I hadn't seen my brother and sister for what seemed to be decades, and, all while I was away from them, I had been with Clary––and I had still missed her the most. I was still worried about her. I was still desperate to see her alive and healthy. Maybe I was so frantic to be with her because, in truth, _I _hadn't really been with her in the time that we were both living with Sebastian. My possessed self had. The same _thing _that had taken control over my body, had kissed _my _girl, had conspired against my family, and had joined forces with an evil psychopath that was responsible for killing Max.

And then the heavenly fire had been discovered and that I couldn't touch _anyone _without hurting them. To avoid having to confront Clary on the matter, I had postponed having to see her for as long as possible––until she'd decided to find a way to see me herself (a little over a three hours ago). As soon as she had walked through those double doors wearing _that _sweater, smelling _that _sweet, and looking _that _beautiful, it had been so hard to restrain myself, to stay leaning against my mass of pillows calm and collected.

I had wanted to devour her. I had wanted to wrap her in my embrace and never let go. But, do you know what had prevented me from doing those things? _Ding ding ding_, we have a winner.

Yeah. The stupid fire.

She'd left the Institute about an hour ago, but––astonishingly–– not without a last kiss. No objections here, it's just that I find it odd that I had been able to touch her curls without catching them on fire and, you know, had been able to press my lips against hers and for Clary to be able to pull away with no more than a little shock. I had burned a _Silent Brother_, but...I hadn't burned Clary. What was it about her that shielded her? Her angel blood?

I could _feel _something different when I was around her, like I couldn't hurt her, like she was immune to my deadly power––not 'immune, but more _resistant_. Whereas with other people I, for some reason, _knew _that I could hurt them, that I'd burn them as soon as we came into contact. And it was truly terrifying; I wanted to be able to hug Alec and Isabelle, give Simon a wedgie, kick whoever I wanted without fearing that they'd turn into a volcano.

Either way, I was going to have to restrain myself at all costs whenever I was around Clary, and all people for that matter. If I hurt anyone that was undeserving, I wouldn't ever be able to forgive myself. _But_, at least for the time being, as long as everyone I cared about was okay and I stayed unpossessed, I was happy––well, as happy as a teenage boy can be when their girlfriend's brother is planning to burn down the world.

* * *

**_Clary_**

By the time I returned home, the sky was a dull gray and dark clouds covered the sun, giving the air around me an eerie atmosphere. _Really__. _My insane brother was on the loose, no doubt fabricating a calamitous scheme to truly burn down the world, and suddenly everything's all Twilight-Zone.

It was almost ridiculous that one simple walk could put a girl in so much distress. The streets of Brooklyn had just been too quiet and calm. Too empty. Every sound made would make me increase my pace, every time a stranger would bump into me, I'd get away from them as fast as humanly possible, and, the poor person selling hotdogs on the side of the street must've thought I was crazy after I flung a bottle of ketchup at him. _Why was I so on edge?_

When Isabelle had asked me earlier if I thought that Sebastian would come back for Jace or me, I had given her an honest answer: _no_. At least not yet. Knowing Sebastian, if he still wanted anything to do with either of us, he was going to want to make sure that he had everything in order before adding any other trouble to the equation. Hands down, Jace was more at risk than I was––which was absolutely terrifying to think about––but, what use was I to my brother––other than being able to create runes? And how profitable would that be if I didn't do it willingly?

But why did something about that still feel off?

Just as I got to the backdoor of Luke's house, my phone vibrated in my pocket, managing to scare the living bejeezus out of me. Juggling the keys to my left hand, I groped for my phone, and, with shaky fingers, held it up to my ear. "H-hello?"

"Clary!" my mother exclaimed, sounding, if not irritable, slightly relieved. "I must've tried you about a dozen times. Are you back from the Institute yet?"

"Yeah, sorry," I stifled, stuffing the keys into the lock, "just got in."

"I've been trying to call to tell you that I just had to run to the store and Luke had to attend an emergency meeting––"

"What for?"

"I'm not really sure. He said that he'd tell me about it once he got back."

"So, I guess I'll be alone then?" I asked, almost dreading the answer. I honestly didn't want to be alone right now. I wanted people _everywhere_, I wanted laughter, incessant chatter, and normal, every-day commotion to go on all around me. Normally, I wasn't a fan of anything loud, but now, anything quiet seemed to be the enemy.

"Only for another thirty minutes or so," she sighed, just as I opened the door. "If I call later on asking if you want anything special for dinner, can I trust you _answer_?"

"_Yes_ Mo––"

Suddenly I was knocked to the ground, the side of my face feeling as if it had been hit with a brick, my vision warping and dilating, battling against a blanket of haze. I whimpered, trying to keep my eyes open long enough for me to see what had hit me, what had happened, _who _had hit me.

"Well that was easier than I thought it would be," a low voice said, erratically growing louder and more hushed all at once.

"Yeah, well, it _should _be easy to break a plate against an unsuspecting girl's face." someone else said, accompanied by a boot nudging my shoulder. "You might've hit her a little too hard, you blockhead."

My thoughts became less swarmed, but I stayed limp, hoping that they would fall for my act and deem me as incapable of protecting myself. I was frightened and confused, wanting nothing more than to be able to run away to my bedroom and hide under my covers like a little girl. _Who were these people? What do they want with me? __Have they been_ following_ me?_

How else would they have known that I'd be home alone at this exact moment?

"_Clary!_" my mother's frantic voice came surging through my senses, sounding muffled and distant._ The phone._ "Clary! Baby! Answer me!"

"Looks like mama bear isn't too happy," one of the strangers chuckled, abruptly silencing my mom's rant––or ending the call. "Get some rope. I want to make sure she won't get away."

"Get away?" his partner scoffed. "Look at her! She's not even forty pounds."

"_Get some_ rope."

They obviously weren't Shadowhunters, or else they would've used runes to bind my hands and feet together, right? But if they weren't Shadowhunters then _what _were they?

He must've listened this time because, very faintly, I could make out a collection of retreating footsteps. Now it was just me and the leader of the two, it seemed. _One on one. _That fact was supposed to be reassuring, but, if anything, it made me all the more scared. _Come on Clary! You're a Shadowhunter for crying out loud! You can fight demons, but not a stupid, burly man?_

Somewhere, in the back of my mind, even if I was trying really hard to block it out, the answer called: _Yes?_

My mom knew that I was in trouble, and I knew that she was inevitably going to show up any minute now. I just had to put up a fight until then. I just had to stay strong, get out of this alive, and ask all of my questions later._  
_

_Just get away._

Not without struggle, I peeled my eyes open, frenetically searching for anything that I could use to defend myself. _Glass_. As discreetly as possible, all while keeping the remaining man in the kitchen in my peripheral vision, I inched my fingers along the cold wood of the ground until I was finally able to grasp a descent sized piece of broken plate.

Very slowly, the man began to approach me. I felt him kneel beside me and snapped my eyes shut, trying not to flinch when his rough fingers grabbed my chin and forced my head to the right, and then to the left. "What a pretty face––"

_Now or never, Clary._

I bolted upwards, lodging the shard of glass, tucked away in my hand, into his thigh, not wasting any time to get on my feet and stride towards the open door. My head pounded, screaming at me to lie down, to stop moving, and my vision was unfocused, but I _had _to escape. However, just as I nearly cleared the threshold, a massive force was propelling me forward.

I went tumbling down the small set of concrete steps, landing harshly on the path with a loud _thud_. "You little bitch," the man seethed, wincing in pain. His feet landed beside my head and I watched––almost as if the world was stuck in slow motion––as one of them reeled back and launched itself at my already-mangled face. "_Bitch_."

It was truly a struggle to keep my eyes open now, but, as my body was lifted into the air and I felt myself being carried back inside the house, I was still awake enough to _feel _the ordeal that I was in. The only thing worse than being hit in the face with a plate and thrown down a set of stairs was demon poison. Then again, demon poison at least assured you that you'd eventually grow numb

I was dropped unceremoniously on the ground in a small heap and heard the door slam closed, its after math ricochetting off of the walls. "Hurry up with the ropes!" my captor growled, letting out a gruff yelp. I was hardly able to make out his large figure sliding to the floor next to me, his hands––one holding a paper towel––clenched tightly around his thigh. "_Agh_."

My mom was going to race into the kitchen at any second now. _Just hold on until then. _However, I had no way of knowing how long 'any second' would be; if she was stuck in traffic or if her car broke down––the latter being highly unlikely––then I'd be screwed if I just gave up now. I needed to draw some time. And fast, before the other guy returned.

I wanted to stay still, in my exact position, for all of eternity. Howbeit that wasn't an option. Begrudgingly, I attempted to move my hand slightly, but their progress felt disoriented and craggy. _There's time to feel pain later. You're a Shadowhunter. Get_ up_!_

"Thought you could get away, did you?" the stranger growled, his voice raising a few octaves, probably unaware of the fact that I was still cognizant. "Caught me by surprise, I'll give you that, but it didn't work sweetheart."

_Why don't I have my stele on me! Or a seraph blade? Or _anything _that any Shadowhunter should have?_

Quicker than I had originally thought, I was springing to my feet and making a break towards the living room. From there, I could either lock myself in the bathroom or hide in Luke's bookstore. Not even a second later, my footsteps had echoes, the man limping after me stringing out curse words and incoherent threats. "_Stop_!"

I slammed into the entrance of the bookshop, barreled through the opening, and hardly managed to stay on my feet as I persisted to run. I meandered in and out between rows until I knew that I had lost my shadow. "You can either come out willingly and save yourself the trouble, or _I _can find you. Your pick," the invader called, his voice turned into a low hiss.

My heart was clawing at my chest, wanting to burst free. A cold sweat coated the back of my neck and unpleasantly rolled down my spine, igniting goosebumps all up and down my arms. I could hear him growing closer, and, being as quiet as possible, I slipped behind yet another shelf, hoping that I had made the right move. I wished that I could see him, but, as if having large barriers between us wasn't enough, it was pitch black, the only light coming from the moon shinning through the glass door. It was a game of cat and mouse, and I, I was the mouse.

"_Wrong answer_," he snarled, having waited a few moments.

I listened carefully as the man stalked further away from me, and, thinking that he had given up––no matter how stupid––I let out a sigh in relief. "Let's see if you can find your way out of this one," he chuckled darkly. _What did he mean––?_

There was suddenly a large eruption, and, while my mind was racing with the possibilities of what that could've been, an unchanging _bang _echoed around the room about every five seconds, until, to my horror, I realized that they were getting closer. Moving on instinct, I darted out from the shelves, landing on my stomach, just in time to hear the final collision of the shelves-turned-dominos collide with the ground, the last two breaking through the opening window. The impact was so loud that I had to cover my ears, and even then, a distracting _ring _persisted in my head.

I tried not to cough, but debris and dust was _everywhere_. With no other option, I clobbered my hand into my mouth, unaware that I was now out in the open, lit by the moonlight. "What a mess," the evil demon said smugly. "It's a good thing you were able to escape––I don't know how I would've explained that one to my boss."

"What do you want from me?" I stifled, backing away on my trembling hands as his figure emerged in the light.

"Oh _I _don't want anything from you," he answered. "But I do want to keep living."

My eyes darted back and forth as I said the first thing that came to mind to distract him. "W-what?"

He took a step forward and the rest of his face was exposed; he wasn't ugly, just not at all good-looking. A nasty, pink scar marked him from the tip of his left eye, to the corner of his mouth. He had disheveled, too-long, brown hair that fell into his dark eyes and a good amount of cuts and bruises that looked like they were on the verge of healing.

"I think you heard me," he smiled, flashing is yellow and crooked teeth. _Yeesh._ "_I want to live_."

"I still don't understand why you need me for that," I bit out, trying to ignore my alarming pain. My eyes suddenly found something of use, shinning brilliantly in the dark: a fire extinguisher.

"But don't you? You see little, foolish Nephilim, this world is going to be submerged in fire––" _Oh, how am I going to get out of this? _This man––whoever he is––works for my brother––who else wants to burn down the world?––or he at least wants to turn me over to him, but why? What ultimately compelled him to find _me_? "––and _no one_––not any Downworlders, not any humans, not any demons, not any unfortunate soul born with the Sight," he spit, "––will survive. However, if I turn _you_ in...I'm guaranteed a future, a future where I'll be of upmost importance and respected, maybe even feared; possibly a leader or apart of the new government. I'll be known as the man who returned _you_ to your rightful home."

Oh God, I was going to be sick.

I had momentarily stopped my progress to absorb everything he had told me. This man couldn't be a Downworlder–– he would've changed forms by now, or, you know, have any distinct indications that he wasn't human––and he couldn't be a demon either, so, the only other possibility was that he had the Sight. "So you actually think that by handing me over to my brother, your life will better from it?" I clarified, incredulous. "He'll kill you. To him, you're weak––what use is a man with Sight going to be to him––?"

"Your brother is not Valentine––"

"No. You're right. He's _not _Valentine. He's much worse," I swallowed, letting my eyes seek out my only source of comfort once more; the fire extinguisher, it was so close and, for such a little thing, it held so much power, so much capability. "And," I continued, taking in a staggered breath, "you'll be sorely disappointed when you find out that he doesn't have any interest in having me by his side." I wasn't completely sure if I was lying or not. Sebastian didn't want me, I wasn't any use to him, I was just a burden if anything. What had happened back at the apartment was creepy, yes, but he couldn't have meant anything he'd said...Right? "If you give me to him, he'll just kill us both and _whatever _this_ is _will have been all for nothing."

_You belong to me._

_Together._

_I think you know better than that._

_You and I, we're alike._

"You don't even know," the man muttered under his breath, shaking his head slightly. "You've been shielded from his wrath––_you've been lucky_––have been enjoying all of your freedom, have taken your abilities for granted. But, your brother, if he's made anything clear, wants _you_." He chuckled darkly, looking me over, his eyes lingering over my trembling form for too long to be considered appropriate. "I have a family, you know," he sighed, never once letting his glare waver. "Two daughters, one not much older than yourself. I have a wife, too...But they were all taken from me," he said bitterly, and, if even possible, I could see an igniting fire within his eyes. "And...the only way I can get them back and promise them a future, is if I make your brother happy.

"I want to give my girls the best possible lives I can, and... I'll do anything to see it through." His story had inevitably drawn my curiosity, despite my intent to get away. Where was Sebastian now, and, if he truly had taken away someone's family, what power had he gained? Were there others like this man? Now, standing not even a foot away, Scarface carefully extended his arm out for mine. "I'm sorry that I have to ruin yours to do so... _But_, business is business. Are you ready to give up and hand yourself over?"

I stared at his offer in what I hoped he perceived as a considerable manner, formulating a plan inside my head as I clasped my hand with his. I let him pull me up a few inches, giving him the allusion that I was going to go along with what he wanted, before I abruptly tugged him forward with all my might and kicked out at his shins. "No way in hell!" I shouted, using my fading adrenaline and momentum to fully mount back to a stand and race towards the fire extinguisher.

With nothing to properly open the glass case, I rashly decided to swing my elbow at the barrier again and again, until there was a large hole, and a whole lot of blood. I yanked the object from its binds and whirled around dizzily to face my opponent. To my surprise, his large build was launching into my own, and I had no time to react before I was being crushed against the wall behind me, and, not even a second later, being pinned to ground.

I distantly heard a door open, and hoped desperately, as I was picked up and thrown at the front desk, that it was my mother or Jace or Luke or _anyone _that could save me.

I struggled to my hands and knees before collapsing, unable to support my weight. I needed time to collect myself, to catch my breath, to _think_, but, of course, I was being picked up again––only this time, by my neck. And then, I heard the most wonderful voice scream my name. "Clary! _Clary_!"

_Jace._

The lights were on in a flash, but I couldn't comprehend anything that was going on around me as I clawed at the hands wrapped around my neck, fighting for air, losing myself more and more by the second. The vice-like hold around me disappeared all at once and I dropped like deadweight to the ground, but I didn't have enough strength to stay aware and slowly slipped into unconsciousness.

* * *

**I'm not sure if I'm happy with this chapter or not. It took me a while to decide if I wanted to post it, but...Hopefully I made the right choice and I'm sorry for making you guys wait so long.**

**I'm going to try to base this fiction off of the summary of the real COHF, snippets, and spoiler art; this means that Jace, Clary and the gang will be traveling to an entire different world, there'll be some pretty intense fight scenes, a ton of romance and lots of CLACE, betrayal, and action(:**

**I really want to make this as accurate as possible, but, I don't know, you guys tell me what you think of this chapter. If I don't get a lot of positive response, I'll probably just take the chapter down and try again!**

**Until next time, peace.**

* * *

**Will be edited soon.**


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